Sleep disturbance can be significant after brain damage due to trauma or stroke, but little is known regarding its prevalence and consequences. Patients often complain of symptoms of disturbed sleep and lack of dreaming, and demonstrate inattentiveness, memory difficulties, and easy fatigability, which are commonly associated with sleep disturbance in uninjured populations. In this protocol the sleep of a representative sample of TBI and stroke patients will precisely characterized, and the findings correlated with independent observations of brain function as delineated through formal neuropsychological evaluation. Subjects will be evaluated while attending the post-acute rehabilitation program of the Transitional Learning Community in Galveston. The results will increase our understanding of brain behavior relationships, and provide a scientific basis for intervening beneficially in these populations with better behavioral and pharmacological therapies Such interventions may directly improve quality of life in these patients and enable them to better engage in other rehabilitation efforts. Because stroke and trauma are leading causes of brain damage in the U.S., and cause considerable disability as well as expenditure for health care and rehabilitation, these results could have major public health impact.